hyperhive/swarm-controller
Repository files (latest commit first)
Filename Latest commit message Latest commit date
atlas 58588a6866 fix(#3412): swarm-controller answers errors as RFC 9457 problem+json
Its three error paths returned a bare string with a status code, which forces
a caller to treat the whole body as prose. hive-c0re converted some time ago,
so swarm-controller was the last backend on the old shape -- and it is the one
behind the hive status page's 503, where the body is frequently the entire
diagnosis rather than a summary.

Adds the commitment to docs/conventions.md, since it was implied by the code
in one daemon and written down nowhere: an endpoint of ours answering with a
bare string is a bug to file, not something callers work around.

The test asserts the rendered response -- media type plus an addressable
detail -- rather than the problem_details value, because a handler that built
the value correctly and then returned it as a string would satisfy a test
written against the type alone.
2026-08-17 21:30:39 +02:00
..
src fix(#3412): swarm-controller answers errors as RFC 9457 problem+json 2026-08-17 21:30:39 +02:00
Cargo.toml fix(#3412): swarm-controller answers errors as RFC 9457 problem+json 2026-08-17 21:30:39 +02:00
README.md docs(gateway): describe what is, not what changed 2026-08-11 18:09:51 +02:00

swarm-controller

The swarm-level daemon. Where hive-c0re owns the agents on one host, this owns what is true across hives — so a swarm runs one of them and most hives leave it off.

Opt-in per host via services.hyperhive.swarm.controller.enable, which is deliberately not derived from services.hyperhive.enable: turning it on is a statement about swarm topology, not about whether hyperhive is installed.

What it does today

Serves one /health endpoint and holds no state.

That is the whole intent of the first slice. The point is to make the unit real — service user, runtime and state directories, socket, nginx reachability — so the swarm-level surfaces that follow have somewhere to land. Inventing those surfaces before they are agreed would bake in a shape nobody chose. See #3066 and the hyperhive.swarm consolidation epic.

Why a unix socket, not a port

The hive-gateway's nginx is the only intended client and reaches the socket through a bind-mount. A listener that is never bound to an address cannot be reached from off-host by mistake.

The socket path is services.hyperhive.swarm.controller.socketPath, default /run/swarm-controller/controller.sock, exported to the process as SWARM_CONTROLLER_SOCKET.

⚠️ The socket's directory is its access control

The socket is 0666. It has to be: nginx runs as a different user and connect(2) needs write. This matches how hive-c0re publishes the per-agent sockets, and rests on the same argument — "the bind source dir is per-agent on host so blast radius is unchanged."

What keeps that safe is that the directory holds one socket. So:

Never point socketPath at a directory that carries anything else. /run/hyperhive above all — it holds host.sock, the host admin socket. Pointing nginx at that directory to reach this socket would put the admin socket within its reach too.

nginx is a host service, so nothing narrows what it can reach except the directory itself — that is the whole of the access control. A unit test pins the default path so a tidying edit fails instead of reviewing cleanly.

RuntimeDirectoryPreserve=yes and the daemon's stale-socket unlink on start are a pair: preserving the directory without the unlink means bind fails with EADDRINUSE after a restart.

Packaging

Built by the workspace derivation and extracted as its own package (nix build .#swarm-controller). Deliberately not in nix/packages' daemonBins — that list is the core stack and drives the bundle services.hyperhive.c0re.package points at, so folding this in would put a swarm-scoped service into every hive's closure.